In-phase implies large likelihood for independent codon model: distinguishing coding from non-coding sequences

It is proven that under the independent codon model, the likelihood of a DNA coding sequence read according to the correct frame is asymptotically larger than that read with an incorrect frame. Based on this proposition, a single set of probabilities of the codon usage is enough for discriminating the six frames of coding sequences under the independent codon model. The direct coding sequence of Escherichia coli genome is taken as an example to examine the codon independency by using the mutual information and chi2 analysis. The contrast between the coding frame and the two offset frames is evident. A self-learning approach for generating training set is proposed to estimate probability parameters.     

Spontaneous decisions and operant conditioning in fruit flies

Already in the 1930s Skinner, Konorskiand colleagues debated the commonalities, differences and interactions among the processes underlying what was then known as “conditioned reflexes type I and II”, but which is today more well-known as classical (Pavlovian) and operant (instrumental) conditioning. Subsequent decades of research have confirmed that the interactions between the various learning systems engaged during operant conditioning are complex and difficult to disentangle. Today, modern neurobiological tools allow us to dissect the biological processes underlying operant conditioning and study their interactions. These processes include initiating spontaneous behavioral variability, world-learning and self-learning. The data suggest that behavioral variability is generated actively by the brain, rather than as a by-product of a complex, noisy input-output system. The function of this variability, in part, is to detect how the environment responds to such actions. World-learning denotes the biological process by which value is assigned to environmental stimuli. Self-learning is the biological process which assigns value to a specific action or movement. In an operant learning situation using visual stimuli for flies, world-learning inhibits self-learning via a prominent neuropil region, the mushroom-bodies. Only extended training can overcome this inhibition and lead to habit formation by engaging the self-learning mechanism. Self-learning transforms spontaneous, flexible actions into stereotyped, habitual responses.     

基于云班课的线上线下混合式教学模式在高职微生物学教学中的探索与实践

随着互联网技术、移动终端设备的迅速发展,线上线下混合式教学模式得到飞快的发展。本文在分析当前高职课程教学存在的问题及解决思路的基础上,介绍了线上线下混合式教学在微生物学课程中的探索与实践,包括线上教学平台的选择、教学内容的重构、教学设计与实施、教学评价与考核等4个方面的内容,最后讨论了线上线下混合式教学的实施效果及反思。线上线下混合式教学采用碎片化教学资源,突破教学的时空限制,提高了学生自主学习能力,提升了微生物学课程的教学质量。